The need for supporting large and heavy signs overhead is at least as old as internal combustion vehicles, and increases with volume and speed of traffic to be directed.
The purpose of such devices is to maintain stability and proper positioning of signs or other objects that have to be accurately positioned in suspension over roadways. This type hanging bracket allows for free swinging movement parallel with roadway to keep legends visible to motorists or pedestrians and must return signs to original position at the conclusion of each gust of wind, with precision, and at all times must hold signs within limits preventing damage to traffic signals, cables carrying electricity and span cables.
Many types of sign supports have been disclosed for overhead use, but the problem of providing a reliable, positively adjustable bracket system for the purpose has remained. Weather effects have tended to wear out the best apparatus prematurely, prior to this invention, which is intended to provide an indefinite life for such suspensions.
A well known type of bracket system illustrating the necessary geometric adjustment and attachment provisions is described in U.S. Pat. No. 2,956,768 issued to S. D. Livingston on 10-18-60. These include, in sequence downward to a sign hung at the bottom: means for attachment to a supporting cable, means for lateral adjustment in a plane defined by the supporting cable, means for adjustment about a vertical axis to set the direction in which a sign is to face, means permitting swinging in the plane in which the sign is to face, and means for attachment of the sign to the bracket.
In U.S. patents of general interest:
No. 2,889,128 to A. S. Martin and J. E. McCleary, 6-2-59, disclosed an "L"-shaped body member in a sign-supporting bracket; PA1 No. 3,891,175 to W. L. Hawley and T. E. Lewis, 6-24-75, disclosed a traffic signal hanger with vertical-axis adjustment; PA1 No. 4,089,129 to W. W. Patterson, Jr., 5-16-78, disclosed a sign hanger with strap-type hinges.